1. Field of the Invention
This invention relates to valves, such as pipeline valves, and more particularly to valves which can combine the advantages of gate valves and of swing check valves.
2. Description of the Prior Art
Various types of valves are known and used in the industry, such as gate valves, swing check valves, etc. Each type of valve is especially suited for a particular application, and is generally known for its advantages and disadvantages.
In U.S. Pat. No. 4,256,283 is shown a pivotal, spherical check valve which is relevant to applicants' invention. In this patent the ball valve has both a linear and rotational movement. It is believed that in such a structure, damage to the ball and to the valve seat will occur causing it to have a relatively short operational life.
In applicants' invention the closure member is non-spherical and has a linear movement followed by a rotational movement, and finally again by a linear movement. In this manner the closure member engages the valve seat substantially simultaneously.
It is a general object of this invention to provide a valve having a non-spherical closure member which moves linearly transversely to the fluid flow, then rotates toward the valve seat, and finally moves linearly parallel to the flowway to sealingly engage the valve seat substantially simultaneously. The closure member can be single-acting, i.e., it can swing in one direction only, or double-acting, that is, it can swing in one direction or in an opposite direction depending on the direction of fluid flow.